Paging windows for power conservation in wireless networks

ABSTRACT

Improved paging for wireless networks is disclosed. A wireless terminal clock is synchronized to a server clock. A paging window and a dormant window are set for communicating between the server and the wireless terminal using the synchronized time. The paging window and the dormant window are set using a set of instructions. During the paging window, a control channel for a cellular network is found by the wireless terminal, and a page is received from the server at the wireless terminal.

This application is a continuation in part of co-pending U.S. patentapplication Ser. No. 11/047,354 entitled PAGING FOR NON-REAL-TIMECOMMUNICATIONS USING CELLULAR NETWORKS filed Jan. 31, 2005.

BACKGROUND OF THE INVENTION

The cellular system was primarily designed to deliver voice and dataservices to the users. Users require real-time responses—that is, when afar end user calls a Wireless Terminal, they expect the WirelessTerminal to ring right away. The cellular system is designed to meetthis need by having the Wireless Terminal look for pages frequently(once every second or so). Cellular networks send pages for specificWireless Terminals in specific frames, and Wireless Terminals may beconfigured to wake-up only during that specific frame to look for thispage and may sleep rest of the time. (A page is an indication from thecellular network to the Wireless Terminal that someone wants tocommunicate with it; a page is typically followed by the establishmentof a communication session). The cellular network requires the WirelessTerminal to wakeup frequently, every second or so, in order to meet theresponsiveness requirements of the user. This consumes substantialbattery power at the Wireless Terminal. In today's cellular network, atypical Wireless Terminal in standby mode (that is when merely listeningfor pages and not having any data or voice communication sessions)depletes the battery within a few days to a few weeks depending on theparticulars of the Wireless Terminal.

However, there are also a number of applications that can use wirelessnetworks that do not require a real-time response; it is acceptable forthe far end to reach the Wireless Terminal(s) within a few seconds,minutes, or hours rather than right away (referred to hereafter asnon-real-time communication). For example, a machine manufacturer maywant to download new data into a machine in the field occasionally,where it is sufficient for this new data to reach the machine within anhour. Or as another example, a courier may want to periodically trackthe location of a piece of cargo which has a GPS location device andWireless Terminal, etc. There is significant value in increasing thebattery life of Wireless Terminals for such applications by leveragingthe fact that this type of communication does not require instantaneousresponse. But, requiring substantial changes to existing cellularnetwork paging methods only for these non-real-time applications is veryexpensive and impractical. It would be useful if paging methods could bedevised which can substantially increase the battery life of WirelessTerminals without imposing substantial changes on the existing cellularnetwork.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention are disclosed in the followingdetailed description and the accompanying drawings.

FIG. 1 is a block diagram illustrating an embodiment of a system forpaging for wireless networks.

FIG. 2A is a block diagram illustrating an example of a mode allocationfor a system for paging in a wireless network.

FIG. 2B is a block diagram illustrating an example of a time allocationfor a system for paging in a wireless network in one embodiment.

FIG. 3 is a flow diagram illustrating an embodiment of a set ofinstructions for determining the paging and dormant windows for a systemfor paging in a wireless network.

FIG. 4 is a block diagram illustrating an example of a time allocationfor a system for paging in a wireless network in one embodiment.

FIG. 5 is a flow diagram illustrating an embodiment of a process tosearch for a communication channel for a system for paging in a wirelessnetwork.

FIG. 6 is a flow diagram illustrating an embodiment of a process forensuring synchronization between the wireless terminal and the server.

DETAILED DESCRIPTION

The invention can be implemented in numerous ways, including as aprocess, an apparatus, a system, a composition of matter, a computerreadable medium such as a computer readable storage medium or a computernetwork wherein program instructions are sent over optical or electroniccommunication links. In this specification, these implementations, orany other form that the invention may take, may be referred to astechniques. A component such as a processor or a memory described asbeing configured to perform a task includes both a general componentthat is temporarily configured to perform the task at a given time or aspecific component that is manufactured to perform the task. In general,the order of the steps of disclosed processes may be altered within thescope of the invention.

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures that illustrate theprinciples of the invention. The invention is described in connectionwith such embodiments, but the invention is not limited to anyembodiment. The scope of the invention is limited only by the claims andthe invention encompasses numerous alternatives, modifications andequivalents. Numerous specific details are set forth in the followingdescription in order to provide a thorough understanding of theinvention. These details are provided for the purpose of example and theinvention may be practiced according to the claims without some or allof these specific details. For the purpose of clarity, technicalmaterial that is known in the technical fields related to the inventionhas not been described in detail so that the invention is notunnecessarily obscured.

An improved technique for paging for wireless networks is disclosed.Wireless terminals are configured to listen for a page for only a shortduration when in standby mode. During the standby mode that is not partof the short duration when listening for a page, the wireless terminalcan disable portions of its circuitry in order to run using less power.The wireless terminal and the other portions of the wireless networkboth understand when the short duration periods for paging are. In someembodiments, a set of instructions is executed both on the wirelessterminal and on a network server that indicates when a wireless terminalis expected to be listening for pages or transmitting messages duringthe standby mode. In various embodiments, the set of instructions forwhen the listening/transmitting short duration of the standby mode hasas parameters one or more of the following: wireless terminal ID, framenumber, broadcast parameters from the cellular network, and subscriberID. In some embodiments, a page request from the cellular networkincludes the wireless terminal ID number for which the page is destinedor addressed to.

In some embodiments, a wireless terminal clock and an internal orexternal server clock are synchronized; a paging window and a dormantwindow for communicating between the server and the wireless terminalare derived using the synchronized time; during the paging window, acontrol channel is found for a cellular network by the wirelessterminal; and, a page may be received at the wireless terminal from theserver. In various embodiments, synchronizing a wireless terminal clockand an internal or external server internal clock comprises the serversending a synchronizing signal to the wireless terminal or synchronizingthe server internal clock to an external time reference andsynchronizing the wireless terminal to the external time reference. Invarious embodiments, the external time reference comprises a globalpositioning system (GPS) time or an Internet time reference via networktime protocol (NTP).

FIG. 1 is a block diagram illustrating an embodiment of a system forpaging for wireless networks. In the example shown, server 102 isconnected to cellular network 100. In various embodiments, cellularnetwork 100 comprises a communication network that communicates usingone or more of the following protocols: global system for mobilecommunication (GSM), general packet radio service (GPRS), enhanced datarates for global evolution (EDGE), code division multiple access (CDMA),time division multiple access (TDMA), wideband code division multipleaccess (WCDMA), and any other appropriate wireless communicationprotocol.

In FIG. 1, in various embodiments, server 102 is connected to thefollowing cellular network elements: in the GSM/GPRS network it can beconnected to the SGSN (Serving GPRS Service Node) or GGSN (Gateway GPRSService Node) or BSC (Base Station Controller), or MSC (Mobile SwitchingCenter); in the CDMA network it can be connected to HA (Home Agent),PDSN (Packet Data Service Node) or BSC (Base Station Controller); in theUMTS (Universal Mobile Telecommunications System) network it can beconnected to SGSN, GGSN or RNC (Radio Network Controller).

In FIG. 1, Server 102 includes a GPS 106 that receives GPS signal 104.In some embodiments, GPS 106 comprises a global positioning systemreceiver that provides a time and position signal to server 102. In someembodiments, server 102 does not include GPS 106 and time and positioninformation is provided to server 102 from other sources such aspreprogrammed position information and time information from theInternet using NTP (Network Time Protocol RFC-1305) or any otherappropriate time reference. Cellular network 100 is connected to one ormore base stations, represented in FIG. 1 by 108 and 110. The basestations communicated with one or more wireless terminals, representedby wireless terminal 114 in FIG. 1. Wireless terminal 114 is able toreceive communication service from cellular network 100 whenever it iswithin the coverage area of an authorized cellular service provider viaa base station. Wireless terminal 114 includes GPS 118 which receivesGPS signal 116. In some embodiments, GPS 118 comprises a globalpositioning system receiver that provides a time and position signal towireless terminal 114. In some embodiments, wireless terminal 114 doesnot include GPS 118 and time and position information is provided towireless terminal 114 from other sources such as position informationfrom the nearest base station and time information from a base station(such as base station 108 or 110), server 102, the Internet using NTP(Network Time Protocol RFC-1305), or any other appropriate timereference. Wireless terminal 114 comprises an internal clock, a cellularmodem and a processor. In some embodiments, the internal clock ofwireless terminal 114 is synchronized to the time signal from GPS 118.In some embodiments, wireless terminal 114 is battery powered.

In some embodiments, server 102 and wireless terminal 114 maintaininternal clocks that are synchronized periodically. In variousembodiments, synchronization is achieved by: both the Server and theWireless Terminal independently receive clock from the same source suchas GPS Satellites, both the Server and the Wireless Terminal receiveclock from the Internet (for example, using Network Time ProtocolRFC-1305), and the Server sends the time to the Wireless Terminal. Insome embodiments, the wireless terminal clock is synchronized to aserver clock by synchronizing the server clock to a first external timereference and synchronizing the wireless terminal to a second externaltime reference, where the first and second external time references areknown and/or expected to be synchronized with each other.

In some embodiments, a server processor synchronizes a server clock witha time reference and derives a paging and a dormant window forcommunicating with a wireless terminal; a wireless terminal processorsynchronizes a wireless terminal clock with a time reference and derivesa paging and a dormant window for communicating with a server via acellular network; a wireless terminal communicates with a server using areceiver and a transmitter to receive pages from and transmit pages to aserver.

In the description below the paging system is described in the contextof the GSM/GPRS cellular system. Although the paging system is describedin the context of the GSM/GPRS cellular system, in various embodimentsthe paging system can be implemented in conjunction with other cellularsystems including enhanced data GSM environment (EDGE), code divisionmultiple access (CDMA), time division multiple access (TDMA), widebandcode division multiple access (WCDMA), and any other appropriatewireless communication protocol.

In various embodiments, the base station requires that the wirelessterminal to indicate it is alive and connected at periodic intervals (alocation update), at irregular intervals, and/or at power up. In someembodiments, if the wireless terminal does not provide a location updatein a periodic manner, the cellular network will start communications upagain with the wireless terminal and deliver messages that have beenqueued up during the time when the cellular network could not delivermessages or pages to the wireless terminal. In various embodiments, theSGSN, a network router, a network device, and/or the server holdsmessages or pages for a wireless terminal in a queue if the messages orpages are not able to be delivered. In some embodiments the locationupdate is provided by the wireless terminal in a manner that is flexibleto the base station. In some embodiments, the location update parameters(for example, times, frequencies, etc.) are broadcast on the controlchannel.

FIG. 2A is a block diagram illustrating an example of a mode allocationfor a system for paging in a wireless network. In the example shown, thewireless terminal (for example, wireless terminal 114 of FIG. 1)operates in two modes: traffic mode and standby mode. During trafficmode, the wireless terminal is communicating with the cellular network(for example, cellular network 100 in FIG. 1) in an active voice or datacommunication session. The traffic mode comprises the standard trafficmode for a cellular network. In some embodiments, during the pagingwindow of the standby mode, the wireless terminal is monitoring forpages destined for it from the cellular network. In some embodiments,during the standby mode the wireless terminal is either in a dormantwindow or in a paging window. For the period of the dormant window, thewireless terminal is in a deep sleep mode. In some embodiments, only thetime clock, the external interrupt monitoring and the timers arerunning. Therefore, the power consumption during the dormant window isextremely small.

FIG. 2B is a block diagram illustrating an example of a time allocationfor a system for paging in a wireless network in one embodiment. In theexample shown, the paging method divides the time into a paging windowand a dormant window. The first paging window starts at time t. Thefirst paging window ends and the second paging window starts at timet+y. The second paging window ends at time t+2y. In this example, thepaging and dormant windows are a fixed time in length (length intime=y). In some embodiments, this division is the 1^(st) tier ofpaging. In some embodiments, the start times and the stop times of thepaging windows and the dormant windows are determined by a set ofinstructions with parameters including one or more of the following: thecurrent time, the wireless terminal identification number (for example,international mobile subscriber identifier), international mobileequipment identifier (for example, device type), and broadcastparameters. In some embodiments, the set of instructions is run on aserver and wireless terminal (such as server 102 and wireless terminal114 of FIG. 1, respectively) so that both have the same definitions ofthe paging and dormant windows. In some embodiments, the paging load ofwireless terminals in the network is distributed by having any givenwireless terminal only interacting with the network during its shortpaging window which occurs sporadically as dictated by a set ofinstructions. In various embodiments, the set of instructions is a fixedset of instructions, is a changeable set of instructions, and/or is adownloadable set of instructions.

In the paging window of FIG. 2B, the cellular network (for example,cellular network 100 of FIG. 1) operates in the manner typicallyemployed (for example, the standard network paging method, referred toherein as the 2^(nd) tier of paging, is used). In the dormant window ofFIG. 2B, the cellular network does not interact with the wirelessterminal; the wireless terminal is made dormant by disabling all or partof its circuitry in order to consume less power. In various embodiments,in the dormant mode the wireless terminal shuts down all circuitry orshuts down all circuitry except that it leaves one or more of thefollowing powered on: its internal clock circuitry, its timer circuitry,and its circuitry to monitor external interrupts. In some embodiments,the clock rate of the circuitry is lowered (for example, divided by two,four, etc.) in order to lower power consumption. In some embodiments,the paging window is very short compared to the dormant window—forexample, the paging window is a few seconds and the dormant window ismany hours—enabling very low power consumption. It should be noted thatthe larger the dormant window, the longer it would take for a message tobe sent or received from a wireless terminal. In various embodiments,the dormant window and paging window are the same lengths over time,change over time (for example, flexible windows, intervals, periods,etc.), are agreed upon between the server and the wireless terminal(such as server 102 and wireless terminal 114 in FIG. 1, respectively),are set by the wireless terminal, are set by the server, are set using aset of instructions, are set using a set of instructions that isdownloaded from the server to the wireless terminal, and/or are signaledindirectly by another control signal.

FIG. 3 is a flow diagram illustrating an embodiment of a set ofinstructions for determining the paging and dormant windows for a systemfor paging in a wireless network. In the example shown, in 300 variableA is computed using the wireless terminal identification number (TID),the Current time in Seconds (TSEC=HH*60*60+MM*60+SS, where HH is hoursranging from 0 to 23, MM is minutes ranging from 0 to 59, and SS isseconds ranging from 0 to 59) and the period for the 1^(st) Tier Period(T1P). Variable A is the result of the sum of TID and TSEC modulo T1P.In various embodiments, the function for variable A is a function of oneor more of the following parameters: TID, TSEC, T1P, and the accesscontrol class for the wireless terminal. In various embodiments, thefunction for variable A comprises a combination of one or more ofvarious functions, including, but not limited to: modulus function,bit-wise XOR function, bit-shifting, addition and multiplication. A is anumber between 0 and (T1P−1). In 302, it is determined if A is equal to0. If A is not equal to 0, then in 304 the process waits until TSEC hasincremented one more second and control passes to 300. If A is equal to0, then in 306 B is set equal to T2P. In 308, it is determined if B isequal to 0. If B is not equal to 0, then in 310 the process waits untilTSEC has incremented one more second, in 312 B is decremented by 1, andcontrol passes to 308. If B is equal to 0, then control passes to 300.

In the example shown in FIG. 3, the modulo operation to compute VariableA accomplishes two objectives: it establishes the 1^(st) tierperiodicity and it makes the start of the page window to be differentinstants for different wireless terminals (an effect achieved by addingthe TID to the TSEC before the modulo operation). This makes the pagingwindow for different wireless terminals to start at different times.This distribution of paging windows over time is essential to maximizethe use of the paging capacity of the cellular network. In this example,the paging window periodicity is T1P and the time length, or duration,of the paging window is T2P. Also, A reaching zero marks the end of theDormant Window and the Paging Window begins. When B reaches zero, thePaging Window ends and the Dormant Window begins.

In some embodiments, the server (for example, server 102 in FIG. 1)transmits the two parameters, Tier-1 Period (T1P) and Tier-2 Period(T2P), that allows the variation of the length of the dormant window andthe paging window durations anytime from the server. For example,depending on the demands of the application, the Wireless Terminal canbe set with different T1P values from the server. So, if the dormantwindow is set to be one hour for a specific wireless terminal, then fora far end that wants to send a page to that wireless terminal, the pagemay have to wait at the server up to 1 hour. So if the applicationrequires longer battery life from the wireless terminal and the page cantolerate a long wait to send a page to that wireless terminal, then theT1P value can be set so that the paging window period is long.

FIG. 4 is a block diagram illustrating an example of a time allocationfor a system for paging in a wireless network in one embodiment. In theexample shown, a number of multiframes occur in the paging window.Multiframes are labeled in FIG. 4 by n−1, n, n+x, and n+2x. The controlchannel broadcasts the multiframes from base stations. There are 52frames that are grouped into a multiframe. Frames are represented by theframes fr0, fr1, fr51, and fr0 in FIG. 4. There are 8 time slots thatare grouped into a frame. Time slots are represented by ts0, ts1, ts7,and ts0 in FIG. 4. There are three paging periods for a specificwireless terminal, which are labeled paging period for wireless terminalA in FIG. 4). There are two intervals between the paging periods, whichare labeled paging interval for wireless terminal A.

In the example shown, for a wireless terminal A, the cellular networkschedules a page only at a particular frame within a specificmultiframe, and only once in every so many multiframes. The exactinstant of the paging period and the interval between the page isderived using a set of instructions where parameters that are input intothe set of instructions include one or more of the following: thewireless terminal identification number, broadcasted parameters from theCellular Network, and the time. The set of instructions is independentlyrun at the cellular network or the server (for example, cellular network100 or server 102 of FIG. 1, respectively) and at the wireless terminalso both can know when the paging period occurs. In some embodiments, thepaging period and paging interval shown in FIG. 4 are on the order offew milliseconds and few hundred milliseconds, respectively.

In some embodiments, the ratio of paging window to dormant windowdetermines the overall power consumption. The smaller the ratio, thelower the power consumption. One way to reduce power consumption is toincreasing size of dormant window (which increases the response time);the other is to reduce the paging window. When a wireless terminalwakes-up from dormant mode, it needs to listen and synchronize to thecontrol channel of the cell within which the terminal presently resides.Since the dormant window can be a long period of time, the wirelessterminal could have moved multiple cells away during this period. It istherefore important to provide a process for rapid searching for thecontrol channel upon wake up from the dormant mode.

FIG. 5 is a flow diagram illustrating an embodiment of a process tosearch for a communication channel for a system for paging in a wirelessnetwork. In the example shown, in 500 the wireless terminal (forexample, wireless terminal 114 in FIG. 1) searches for a control channelto communicate with the network (for example, cellular network 100 inFIG. 1) first by trying the last channel. In 502, the last neighbor list(a list of channels neighboring the last channel) is searched for acontrol channel on which to communicate with the cellular network. Insome embodiments, the control channel in the cellular system broadcaststhe control channel numbers of the surrounding cells (called theneighbor list). In 504, the last 10 control channels camped on excludingthe last control channel and control channels on the last neighbor list.In 506, an exhaustive search is performed for a control channel. Invarious embodiments, the process searches a list of control channelsbased on a location provided by GPS location information, a list ofcontrol channels based on a location provided by the cellular network(for example, by receiving a signal from a nearby base station), a listof control channels from all past locations, and/or a list of controlchannels from a list of anticipated locations or preprogrammedlocations.

FIG. 6 is a flow diagram illustrating an embodiment of a process forensuring synchronization between the wireless terminal and the server.If a wireless terminal and a server are not synchronized—for example, ifthe clock on the wireless terminal is inaccurate due to temperaturechanges, then there is a possibility that the wireless terminal andserver will not have synchronized dormant window and paging windows.This could lead to a situation where the wireless terminal and server donot communicate. In the example shown, in 600 a countdown timer isloaded with a timeout interval value and started. The countdown timerestablishes a timeout window, which if the wireless device has notreceived a page or has communicated with the server, the wirelessterminal will initiate communication with the server and check to see ifthere are any queued pages for it and check to see if its clock is stillsynchronized with the server or requires recalibration by communicationwith the server. In 602, it is determined if the wireless terminal hasreceived a page or has communicated with the server. In the event thatthe device has received a page or has communicated with the server, thencontrol passes to 600. In the event that the wireless terminal has notreceived a page or has not communicated with the server, then controlpasses to 604. In 604, it is determined if the countdown timer hascounted down to zero. If the countdown timer has not counted down tozero, then control passes to 602. If the countdown timer has counteddown to zero, then in 606, the server is contacted and information isretrieved regarding queued pages. In 608, pages are retrieved from theserver by communicating with the server to see if any pages are queuedfor being sent to the wireless terminal and if so they are retrieved. In610, the clocks of the server and the wireless terminal are synchronizedif they are not already synchronized, and control passes to 600. Invarious embodiments, the communication with the server uses a packetswitched network such as GPRS, EDGE, WCDMA, a paging network such asSMS, or any other appropriate network. In some embodiments, thecommunication with the server enables the wireless terminal the serverto change the paging window, the dormant window, and/or the timeoutwindow during the communication with the server. In some embodiments,the communication with the server enables the wireless terminal torecalibrate its clock.

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, the invention is not limitedto the details provided. There are many alternative ways of implementingthe invention. The disclosed embodiments are illustrative and notrestrictive.

1. A method of paging for wireless networks comprising: synchronizing awindow clock of a wireless terminal to a server window clock, whereinthe server window clock is separate from and is only synchronizedperiodically with the window clock of the wireless terminal; determiningwhether the wireless terminal is in a traffic mode or a standby mode; inthe event that the wireless terminal is in standby mode, determiningwhether the window clock of the wireless terminal indicates that thewireless terminal is in a paging window or in a dormant window using aset of instructions, wherein the paging window has a duration at leastas long as a duration from a start of a first paging slot to an end of asecond paging slot between the wireless terminal and the server suchthat the paging window overlaps at least one paging slot between thewireless terminal and a base station, and wherein the dormant window hasa duration greater than at least twice a period between the first pagingslot and the second paging slot, wherein the period between the firstpaging slot and the second paging slot is based at least in part on apaging clock of the base station or a paging clock of the wirelessterminal; and in the event that the wireless terminal is in the dormantwindow, maintaining sleep of the circuitry of the wireless terminal andnot waking up circuitry for any paging slots between the wirelessterminal and the server; in the event that the wireless terminal is inthe paging window: waking up circuitry to receive and to respond to thepage; determining a paging interval and a paging period, wherein thepaging interval is based at least in part on a function of the wirelessterminal identifier, a time, and a first paging period to distribute apaging load of the wireless network; listening for the page during thepaging period occurring at a time based at least in part on the paginginterval; receiving the page from the server at the wireless terminal ifand only if a message is sent from the server to the wireless terminal;and causing the circuitry of the wireless terminal to sleep.
 2. A systemof paging for wireless networks comprising: a wireless terminal, whereinthe wireless terminal includes a window clock; a server for a cellularnetwork, wherein the server includes a window clock, wherein the windowclock of the server clock is separate from and is only synchronizedperiodically with the window clock of the wireless terminal; and aprocessor; and a memory coupled with the processor, wherein the memoryis configured to provide the processor with instructions which whenexecuted cause the processor to: synchronize a clock of a wirelessterminal to a server clock; determine whether the wireless terminal isin a traffic mode or a standby mode; in the event that the wirelessterminal is in standby mode, determine whether the clock of the wirelessterminal indicates that the wireless terminal is in a paging window orin a dormant window using a set of instructions, wherein the pagingwindow has a duration at least as long as a duration from a start of afirst paging slot to an end of a second paging slot between the wirelessterminal and the server such that the paging window overlaps at leastone paging slot between the wireless terminal and a base station, andwherein the dormant window has a duration greater than at least twice aperiod between the first paging slot and the second paging slot, whereinthe period between the first paging slot and the second paging slot isbased at least in part on a paging clock of the base station or a pagingclock of the wireless terminal; and in the event that the wirelessterminal is in the dormant window, maintaining sleep of the circuitry ofthe wireless terminal and not waking up circuitry for any paging slotsbetween the wireless terminal and the server; in the event that thewireless terminal is in the paging window: wake up circuitry to receiveand to respond to the page; determine a paging interval and a pagingperiod, wherein the paging interval is based at least in part on afunction of the wireless terminal identifier, a time, and a first pagingperiod to distribute a paging load of the wireless network; listen forthe page during the paging period occurring at a time based at least inpart on the paging interval; receive the page from the server at thewireless terminal if and only if a message is sent from the server tothe wireless terminal; and cause the circuitry of the wireless terminalto sleep.
 3. A system as recited in claim 2, wherein the set ofinstructions is set by the server.
 4. A system as recited in claim 2,wherein the set of instructions is set by the wireless terminal.
 5. Asystem as recited in claim 2, wherein the set of instructions isdownloaded from the server to the wireless terminal.
 6. A system asrecited in claim 2, wherein the set of instructions is selected by acontrol signal.
 7. A system as recited in claim 2, wherein the set ofinstructions includes a modulo function.
 8. A system as recited in claim2, wherein the set of instructions includes a bitwise-XOR function.
 9. Asystem as recited in claim 2, wherein the set of instructions includesusing a wireless terminal identifier as a parameter.
 10. A system asrecited in claim 2, wherein the set of instructions includes using asubscriber identifier as a parameter.
 11. A system as recited in claim2, wherein the set of instructions includes using the synchronized timeas a parameter.
 12. A system as recited in claim 2, wherein the set ofinstructions includes using a paging window periodicity as a parameter.13. A system as recited in claim 2, wherein the set of instructionsincludes using a time length of the paging window as a parameter.
 14. Asystem as recited in claim 2, wherein the set of instructions is a fixedset of instructions.
 15. A system as recited in claim 2, wherein findingthe control channel for the cellular network includes searching a listof control channels based on a location provided by GPS locationinformation.
 16. A system as recited in claim 2, wherein finding thecontrol channel for the cellular network includes searching a list ofcontrol channels based on a location provided by the cellular network.17. A system as recited in claim 2, wherein finding the control channelfor the cellular network includes searching a list of control channelsfrom all past locations.
 18. A system as recited in claim 2, whereinfinding the control channel for the cellular network includes searchinga list of control channels based on anticipated locations.
 19. A systemas recited in claim 2, wherein finding the control channel for thecellular network includes searching a preprogrammed list of controlchannels.
 20. A system as recited in claim 2, further comprisingproviding to a base station from the wireless terminal a locationupdate.
 21. A system as recited in claim 2, wherein synchronizing thewireless terminal clock to the server clock comprises synchronizing thewireless terminal clock to a first external time reference andsynchronizing the server clock to a second external time reference,wherein the first and second external time references are synchronizedwith each other.
 22. A system as recited in claim 2, wherein during thedormant window the clock rate is lowered to conserve power.
 23. A systemas recited in claim 2, wherein the processor is further configured toinitiate communication with the server if no page has been receivedwithin a timeout interval.
 24. A system as recited in claim 23, whereinthe communication includes information to synchronize the wirelessterminal window clock to the server window clock.
 25. A system asrecited in claim 23, wherein the communication includes information torecalibrate the wireless terminal window clock.
 26. A system as recitedin claim 23, wherein the communication includes information about pagesto be sent to the wireless terminal.
 27. A system as recited in claim23, wherein the communication includes information to change one or moreof the following: the paging window, the dormant window, and the timeoutinterval.
 28. A system as recited in claim 23, wherein the communicationuses a packet switched network.
 29. A system as recited in claim 23,wherein the communication uses one or more of the following: a GPRSpacket switched network, an EDGE packet switched network, and a WCDMApacket switched network.
 30. A system as recited in claim 23, whereinthe communication uses a paging network.
 31. A system as recited inclaim 23, wherein the communication uses a SMS paging network.